Replace some hard coded schemes with the constants in /url/url_constants.h.

content/browser/loader/resource_scheduler.cc

Index: content/browser/loader/resource_scheduler.cc
diff --git a/content/browser/loader/resource_scheduler.cc b/content/browser/loader/resource_scheduler.cc
index 0d54b7b106d7e93ab0c8837a5ed3f17bcaa91090..0dd93f32f64e82a8ce933f38b7168f59f6dbd6f4 100644
--- a/content/browser/loader/resource_scheduler.cc
+++ b/content/browser/loader/resource_scheduler.cc
@@ -613,7 +613,7 @@ class ResourceScheduler::Client {
       return DO_NOT_START_REQUEST_AND_STOP_SEARCHING;
     }
 
-    if (using_spdy_proxy_ && url_request.url().SchemeIs("http")) {
+    if (using_spdy_proxy_ && url_request.url().SchemeIs(url::kHttpScheme)) {
       return START_REQUEST;
     }